If you think of all of them as starting from a tilted/uneven flare...after reaching the position, you give the higher wing a sharp and short input, step forward, watch it spin, step back and fly off.
The 540 reaches the flare from a...flare. You step forward and have one hand extended and one hand back when you initiate the spin. This turns out to be true in all three tricks.
The slot machine and taz both use a half axel to achieve the flare. The spin input in the slot happens at the start of the half axel, and in the taz it happens near the end of the half. Because it requires getting a consistently correct position at the end (as opposed to the very beginning) of the half axel, the taz is a bit harder. The spins are always best initiated with a sharp and short accelerating input. The slot machine rotates counter to the half axel rotation, so the second input is clearly visible when the kite starts to rotate. The taz continues the half axel rotation, and very beautiful taz machines appear to just spin with hardly a spin input visible.
Some evidence this works is that if you get real good at this style slot machine, you can often allow it to over rotate and exit straight up, or even back the other way, just like a 540 that goes too far.
I can only sometimes nail the taz so well. I found that if anything, the input for the spin in the taz is the shortest and sharpest. I have had nothing but fun seeing how far I can get a slot to spin.